I am so surprised how many people prefer the G5 to the G7. I wonder if they just purchased the mouse before the G7 came out, or maybe because it's cheaper? Although less so now than in the past.
I confess, the G7's battery life is not nearly as long as some mentioned in this post (maybe 4 or 5 hours of solid gaming, but I have never measured it honestly). However, because it comes with two batteries I find this to be a minor inconvenience. I imagine there must be SOME lag with this cordless mouse, but I honestly cannot notice it. I have been using it for months now, and I would NEVER go back to a corded mouse. the cords have always driven me crazy, and I was always aware of the feel of the wire drag (even when I reduced it as much as I could).
I can switch my mouse battery so fast, I do not die even in BF2. True, there is a minor chance you could run out of battery power and die, but if it was any kind of an important tournament game or something, you'd obviously have swapped out the battery to the freshly charged one before beginning.
The mouse is comfortable, accurate, and when the teflon pads on it are new it feels SO smooth. I also agree the DPI adjustment is a great addition for games like BF2 for the tank turrets and for sniping at long distances occasionally. I will stand out and be different, by recommending the G7. I have tried the G5 and find it to be equal in every respect, except for that irritating mouse cord. If your mouse cord never bothers you, buy the g5.